摘要:

ABSTRACTA commercial oxygen reducing membrane fraction obtained from Escherichia coli (OxyraseTM) has been shown in our laboratory to stimulate growth of many facultative anaerobic organisms, including starter cultures. The purpose of this study was to isolate “Food Grade” membrane fractions from Acetobacter xylinum and Gluconobacter oxydans and to compare their activities with the membrane fractions from E. coli prepared in our laboratory and Oxyrase. Cells were grown in afermentor, harvested by centrifugation, and disrupted by a French press (ca. 15,000 psi). The suspension was fractionated and filtered before use. The maximum activity of membrane fractions of Gluconobacter and Acetobacter were from cultures grown to 24 and 44 h, respectively. Formate, lactate, succinate, and α‐glycerophosphate were tested as H‐donors for enzyme activity. When lactate and α‐glycerophosphate were used as substrates, Acetobacter membrane fractions were able to deplete 100% oxygen in 5 min. It required 8 and 30 min, respectively, when succinate and formate were used. Gluconobacter membrane fractions were effective with lactate and α‐glycerophosphate. With succinate and formate, they took about 60 min or longer to reduce O2completely. E. coli membrane fractions made in our laboratory depleted O2more effectively (1 min) than Oxyrase (3–5 min) when formate was u

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00305.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTMany methods have been developed to determine microbial levels in food products and these include ATP bioluminescence, hydrophobic grid membrane filtration (HGMF), impediometry and turbidimetry. A comparison of these techniques for detecting microbial levels in chicken carcass rinses was conducted.Only the ATP bioluminescence assay and the HGMF system showed a good correlation with plate counts (r = 0.82 and r = 0.83, respectively). The repeatability of these methods was acceptable. There was also a significant correlation between results obtained with two turbidimetric methods and HGMF as well as between HGMF and ATP bioluminescence data. However, only the ATP bioluminescence assay was able to provide results of microbial levels on a realtime basis (within 10 min). This would be beneficial for HACCP (Hazard Analysis of Critical Control Points) based programs.

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00306.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe sensitivity of the original versus the modified Salmonella‐Tek enzyme immunoassay (EIA) was compared for recovery of Salmonella spp. from selected low‐moisture foods. Serial tenfold dilutions were inoculated into incubated post enrichment media (dilution‐to‐extinction approach). Results indicated no significant difference between the original and modified Salmonella‐Tek EIAs. A comparison of the modified Salmonella‐Tek EIA and the modified GENE‐TRAK Salmonella assay, using the same approach, also showed no significant differences.The effectiveness of the assays was then compared using a second approach (dry bulk inoculation). A lyophilized culture was inoculated into bulk food. Replicate 25‐g test portions were used in a 3‐way comparison of the effectiveness of the modified Salmonella‐Tek EIA, the modified GENE‐TRAK Salmonella assay, and the standard culture method approved by the Association of Official Analytical Chemists (AOAC) International and recommended in the Food and Drug Administration's Bacteriological Analytical Manual. Of 460 test portions examined, 307 gave positive reactions with the modified Salmonella‐Tek EIA, 298 with the modified GENE‐TRAK Salmonella assay, and 292 with th

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00307.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTWe have developed a rapid method for the determination of lag times and specific growth rates for bacteria. This method involves the use of a Bio‐Tek model EL312 microtiter plate (MP) reader, controlled by KinetiCalc software, and uses a computer program that processes absorbance data from a 96‐well MP. The program reads an ASCII file consisting of optical density readings generated by the MP reader, sorts the data into individual growth curves, and determines growth kinetics. No statistically significant difference (P>0.88) was found between the MP method and standard batch methods. This method allows up to 95 growth curves to be carried out simultaneously. The MP method automates the difficult task of determining growth kinetics for bacterial strains under conditions that result in slow growth rates or long lag times. Using this method we determined the effect of NaCl on the growth kinetics of Listeria monocytogenes and the effects of NaCl and temperature on the growth kinetics of Leuconostoc mesenteroi

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00308.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTA total of 215 freshly processed post‐chill whole chicken carcasses were assessed for Campylobacter spp. contamination by a fluorescence concentration immunoassay (FCIA) procedure. Whole chicken carcasses were sampled with low volume water rinses from which 5 ml portions were enriched with brucella enrichment broth with or without oxyrase supplement in a test tube enrichment system. After a 24h stationary incubation at 42C, each sample was assayed using a FCIA procedure for the presence or absence of campylobacters. The FCIA procedure indicated Campylobacter spp. contamination in 84% of carcasses using oxyrase supplemented enrichment, while only 47% of the chicken carcasses were positive from nonsupplemented enrichment. The corresponding incidence rates detected by culture method were 92% and 87% for oxyrase supplemented and unsupplemented samples, respectively. The FCIA procedure can be completed in less than 1 h with 48 samples including a positive and a negative control assayed on one plate. In summary, the test tube oxyrase‐supplemented stationary enrichment system followed by the use of the FCIA procedure was found to be an effective, rapid method for the detection of Campylobacter spp. in chicken rinse wa

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00309.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe viable cell count performance of nutrient agar prepared by the MikroClaveTM sterilization system MSS‐500 was evaluated using Escherichia coli 0157:H7, Salmonella typhimurium, and Yersinia enterocolitica with conventionally autoclaved media as a comparison. No significant difference was found between agar prepared by the two methods. The MikroClaveTM was able to sterilize common bacteriological media such as Eosin Methylene Blue (EMB) agar, nutrient agar, Yeast and Mold (YM) agar, lactose broth, nutrient broth, and Yeast and Mold (YM) brot

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00310.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Rapid Methods and Automation in Microbiology and Immunology. edited by R.C. Spencer, E.P. Wright, S.W.B. Newsom.

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00311.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1994.tb00304.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY